\documentclass{standalone}
\usepackage{tikz}
\usepackage{ctex,siunitx}
\setCJKmainfont{Noto Serif CJK SC}
\usepackage{tkz-euclide}
\usepackage{amsmath}
\usetikzlibrary{patterns, calc}
\usetikzlibrary {decorations.pathmorphing, decorations.pathreplacing, decorations.shapes,}
\begin{document}
\small
\begin{tikzpicture}[>=stealth,scale=1.0]
  % \useasboundingbox(-1,-2)rectangle(8,6);
  \fill [lightgray](-3,-2) rectangle(3,2);
  \draw [fill=white] (0,0) ellipse [x radius=1.5, y radius=0.75];
\end{tikzpicture}
\end{document}